System for generating steam



Sept. 11, 1945. V .1. P. BADENHAUSEN 2,384,537

SYSTEM FOR GENERATING STEAM Filed Feb. 16, 1944 IN V EN TOR.-

Patented Sept. 11, 1945 UNITED STATES PATENT OFFICE 9 Claims.

This invention relates to systems for enerating steam and moreparticularly to such systems for generating and delivering steam freefrom objectionable carry-over of solids content.

In accordance with the present invention provision is made for thecontinuous generation of steam of high purity free from objectionables01- ids content.

In accordance with the present invention also, provision is made forsegregating and separating the extraneous solid materials in solid andin liquid form so that the same may be readily removed from time totime.

In accordance with the present invention also, provision is made for thecontinuous operation of high capacity steam generators without thenecessity of shutdown for cleaning.

The present invention also contemplates the provision of simpleapparatus for providing steam of higher purity than has heretofore been.obtained.

The invention further contemplates apparatus capable of use withexisting installations for overcoming troubles heretofore encountered.

Other objects of the invention will be apparent from the annexespecification and claims.

The nature and characteristic features of the invention will be morereadily understood from the following description, taken in connectionwith the accompanying drawing forming part hereof, in which:

Figure 1 is a diagrammatic view of a power plant known to the art whichis included for purposes of explanation of the invention; and

Fig. 2 is a diagrammatic view of a preferred embodiment of the presentinvention.

It will, of course, be understood that the description and drawingsherein are illustrated merely, and that various modifications andchanges may be made in the structure disclosed Without departing fromthe spirit of the invention.

Referring more particularly to Fig. 1 of the drawing a typical powerplant is illustrated diagrammatically which includes a steam generatorID, a turbine H to which steam is supplied from the steam generator I!)through a steam main I6, a condenser |2 for receiving exhaust from theturbine II, a return line |8 for the condensate, a make-up evaporator |3heated by steam tapped from the turbine H at the desired stage anddelivered through a pipe l1, and a feedwater heater H, the water formake-up being supplied to the make-up evaporator 3 through a pipe I5. Inaddition to the foregoing there is also shown a 10 superimposed steam 5of the character employed in many modem or modernized steam powerplants.

In the operation of the lower pressure portion of the system includingthe steam generator It, the turbine H and the condenser 2, without agenerator 20 and topping turbine 2| n0 difficulties are encountered withthe deposit of solids in the turbine H. In systems employing asuperimposed steam generator 20 and a topping turbine 2|, difiicultieshave been encountered not only in the superimposed steam generator wherethe presence or deposition of solid materials has caused unexpected tubefailures, but also by reason of the carrying over from the steamgenerator 20 of certain solids which have deposited at certain locationsin the system. No deposit has been noted in the topping turbine 2| butsolid materials have deposited in the main turbine usually at a locationwhere the temperature ranges from approximately 585 F. to 600 F. and ata pressure below approximately 275 pounds. Analysis of the depositstaken from the turbine blading indicated that the principal constituentswere sodium hydroxide and sodium silicate although other boiler watersalts were also found to be present. The solids deposited did nothowever reflect the same percentage of materials as those found in theboiler water.

Apparently upon the raising of the temperature and pressure of the steamto the high ranges required for the operation of topping turbines, suchas the turbine 2|, some dissociation or vaporization of the saltstherein occurs and upon subsequent reduction in temperature and pressurethese materials are redeposited in the system in solid form. Thevelocity of flow of the steam particularly in the turbine I does notseem to be adequate for preventing such deposition.

Numerous instances have been recorded in which the output capacity ofturbines has been continuously decreased by the deposit of solids, andto an extent of more than one-quarter in one months time. In otherinstances turbines have been out of service for considerable periods oftime because of the solids deposited therein.

Various attempts have heretofore been made to remedy the situation.Washing of the steam with feedwater has been tried with only indifierentsuccess. It has also been suggested that the feedwater treatment shouldbe changed, but such changes have not produced any very markedimprovement.

In a steam generating system such as those employed in central stationservice where the quantitles of steam are large and of the order of amillion pounds of steam in from one to ten hours, and where the make-upis of the order of 2 or 3% the continuous introduction of even arelatively small quantity of solid material has a cumulative effectwhich may quickly become troublesome.

Referring now more particularly to Fig. 2, the power plant there showndiagrammatically, includes a steam generator I and main steam turbine IIand a condenser I2 with provisions such as the line l8 for returning thecondensate for continuous generation of steam. The superimposed steamgenerator 20 supplies steam to the topping turbine 2| which dischargesto the main steam turbine ll. While two separate turbines areillustrated at 2| and II, it will, of course, be understood that thesame could be readily embodied in a single casing with interstage supplyof the steam from the steam generator In.

In accordance with the present invention and for the purpose ofsupplying water of high purity for make-up, as well as for the initialsupplying of water of high purity for operation of the system, aprecipitator 30 is provided which is adapted to generate steam,preferably at a higher temperature and pressur than that of thesuperimposed steam generator 20, for the purpose of retaining in theprecipitator 30, in solid and in liquid form, certain of the materialsheretofore carried over in the steam. The precipitator 30 is preferablya steam generator capable of retaining such materials and capable ofbeing readily cleaned and for this purpose a precipitator such as thatshown in my priorapplication for Letters Patent filed December 22, 1943,Serial No. 515,245, or in my prior application for Letters Patent forSteam generating systems filed February 16, 1944, Serial No. 522,556,may be employed.

The precipitator 30 is of much smaller size than either of the steamgenerators 20 and I0 and has a capacity such to provide the requisitemake-up for the system. The precipitator is preferably connected by asteam line 3| to a turbine 32 for the expansion of the steam to apredetermined level of pressure and temperature and for the extractionof the energy during the expansion. The turbine 32 is connected to adesuperheater or cooling unit 33 for the purpose of reducing itstemperature, if required, to the desired range. The unit 33 is connectedto a collecting chamber or tower 3'4 such for example as that shown inmy application for Letters Patent for Steam generating systems, filedFebruary 16, 1944, Serial No. 522,556, although any other suitablecollector for the solids content of the steam may be employed. The tower34 is connected to discharge steam to a heat exchanger or indirectlyheated steam generator 35 such for exampleas that shown in my priorLetters Patent for Steam generators, No. 2,336,832, issued December"14,-1943. The pipe 35 is provided for supplying the raw water which,after heating or in the form of steam, is supplied through the pipe '31to the steam generator 30. The condensed steam from the heat exchanger35 discharges through a pipe 38 and is supplied as makeup to the powerplant through a supply pipe 39. If desiredfa portion of the condensatefrom the pipe 38 may be employed in the desuperheater or cooling unit33, the pipe 40 being provided for delivery thereof,

The operation of the system in accordance with the present inventionwill now be pointed out, reference being had particularly to Fig. 2.

The steam generator 10 may be operated to deliver steam at a temperatureof the order of 750 F. and at a pressure of the order of 275 pounds. Thesteam generator 20 may be operated to supply steam at a pressure of theorder of 1,250 pounds and at a temperature of the order of 920 F. andwater is supplied to the steam generator 10 and to the steam generator20 at a temperature of the order of 400 F. The turbines 2i and II areoperated by the steam supplied thereto from the steam generators 20 andi0 and the condensate from the condenser 12 is returned through the linel8.

For the purpose of supplying make-up free from solids content theprecipitator 30 is preferably operated for the generation of steam at apressure several hundred pounds higher than that of the steam suppliedby the steam generator functioning at the highest pressure required bythe turbine 2i. The precipitator 30 may be operated at a pressure of theorder of 1,800 pounds and at a temperature of the order of 920 F. Theprecipitator 30 is supplied with water as hereinafter set forth inaccordance with the make-up requirements through the line 31 and thetemperature of the water thus supplied may be of the order of 400 F.

The raising of the temperature of the fluid within the precipitator 30in the range from approximately 400 F. to approximately 920 F., withgeneration of steam at a pressure of the order of 1,800 pounds, willcause certain of the contaminating solids to be segregated so that theymay be retained in the precipitator 30 in the form of solidincrustations on the tube walls and also dissolved in the water. By thischaracter of operation the solids are not delivered in appreciablequantity beyond the precipitator 30. The separated and segregated solidsdeposited in solid form as tube incrustations may be removed by cleaningthe tube surfaces of the precipitator 30 and the solids in dissolvedform may be removed by discharging the water containing the same fromthe precipitator 30. Certain of the solids at high temperature ranges,as heretofore indicated, are vaporized or sublimed.

The steam from the precipitator 30 passes to and through the turbine 32which for a fiow of steam of the order of 30,000 pounds per hour will becapable of generating approximately 1,000 kw. The pressure is reduced inpassing through the turbine 32 to approximately 275 pounds and thetemperature is reduced to approximately 599 F. The temperature isfurther reduced, but preferably not below about 585 F., at thedesuperheater or cooling unit 33 by water sprayed therein from the pipe40. This reduction will be effective for throwing down the solidscontent which may have carried over from the precipitator 30. The solidscontent will be in the form of precipitates or incrustations or othersolid form. The reduction of temperature and pressure in the turbine to599 F. and 275 pounds will bring the steam approximately to the rangewhere the solids may be separated and collected. The furtheir reductionof temperature and pressure in the desuperheater or cooling unit 33 willbe effective for this purpose and the solids thus separated arecollected in the tower 34 in the form of precipitates or incrustationson the surfaces therein. The collected material may be removed from timeto time as desired.

The steam freed of the remainder of the solids content is thenpreferably utilized for heating the feedwater supplied to theprecipitator 30 through the pipes 36 and 31 to a temperature of theorder of 400 F. The condensate is available in the lines 38 and 39 forsupplying Water, free from solids content, to the power plant throughthe line 39.

The operation of the precipitator 30 at a higher temperature andpressure range than that of the superimposed steam generator or highestpressure steam generator of the power plant permits of the separation ofsolid materials prior to the delivery of motive fluid for makeup to themain power plant and such solids as are carried in vapor form with thesteam are collected and segregated at the tower 34 in an efiectivemanner. At the same, time the energy available in connection with thepreparation of the makeup of high purity is effectively utilized.

I claim:

1. Apparatus for supplying make-up to a closed motive fluid circuitpower plant having a high capacity main steam generator thereinincluding a second steam generator for generating steam at a higherpressure than said main steam generator, expanding means including aprime mover connected to said second steam generator, means for reducingthe pressure and temperature of the steam from said prime mover, and achamber for receiving steam from said reducing means and for collectingsolid materials carried by said steam, and fluid delivery connectionsfrom said chamber to said main steam generator.

2. Apparatus for supplying make-up to a closed motive fluid circuitpower plant having a high capacity main steam generator thereinincluding a second steam generator for generating steam at a higherpressure than said main steam generator and for retaining solidmaterials, expanding and power extracting means connected to said secondsteam generator, pressure and temperature reducing means connected tosaid expanding means, and means connected to said reducing means forcollecting solid materials carried by said steam, and fluid deliveryconnections from said collecting means to said main steam generator forthe delivery thereto of fluid free from solid materials.

3. Apparatus for supplying make-up to a closed motive fluid circuitpower plant having a high capacity main steam generator thereinincluding a second steam generator for generating steam at a higherpressure than said main steam generator and for retaining solidmaterials, means connected to said second steam generator for expandingthe steam from said second steam generator and for reducing thetemperature and pressure of the steam, means for receiving steam fromsaid expanding and reducing means and for collecting solid materialscarried by said steam, means for condensing the steam freed of the solidcollected material and for feeding the same to said main steamgenerator.

4. Apparatus for supplying make-up to a closed circuit steam systemhaving a high capacity main steam generator therein including anadditional steam generator for generating steam at a higher pressurethan said main steam generator and for retaining solid materials, meansfor reducing the pressure and temperature of the steam from saidadditional steam generator and for extracting power therefrom duringsaid reduction, means for collecting solid materials thrown down by saidreduction, a heat exchanger for condensing said steam for said make-upand for heating the fluid supplied to said additional steam generatorwith residual heat from said steam, and fluid delivery connections fromsaid heat exchanger to said main steam generator for the deliverythereto of condensate freed of solid materials.

5. Apparatus for supplying make-up to a closed circuit steam systemhaving a high capacity main steam generator therein including anadditional steam generator for generating steam at a higher pressurethan said main steam generator and for retaining solid materials, meansfor reducing the pressure and temperature of the steam from saidadditional steam generator and for extracting power therefrom duringsaid reduction, means for collecting solid materials thrown down by saidreduction, a heat exchanger for heating the fluid supplied to saidadditional steam generator with residual heat from said steam, and fluiddelivery connections to said mainsteam generator for the deliverythereto of make-up free of solid materials.

6. Apparatus for supplying make-up to a closed circuit steam systemhaving a high capacity main steam generator therein including anadditional steam generator for generating steam at a higher pressurethan said main steam generator and for retaining solid materials, meansfor reducing the pressure and temperature of the steam from said steamgenerator and for extracting power therefrom during said reduction,means for collecting solid materials thrown down by said reduction, aheat exchanger for condensing the steam from said collecting means forsaid make-up, and fluid connections from said heat exchanger for thedelivery of said make-up.

7. Apparatus for supplying condensate of high purity including a steamgenerator for collecting and retaining solid materials in solid andliquid form, means including a prime mover for reducing the pressure andtemperature of the steam from said steam generator, means for collectingsolid materials thrown down by said reduction, and means including aheat exchanger for condensing the fluid from said collecting means.

8. Apparatus for supplying condensate of high purity including a steamgenerator for collecting and retaining solid materials in solid andliquid form, means for reducing the pressure and temperature of thesteam from said steam generator, means for collecting solid materialsthrown down by said reduction, and means including a heat exchanger forcondensing the fluid from said collecting means.

9. Apparatus for supplying condensed steam of high purity including asteam generator, means including a prime mover for reducing the pressureand temperature of the steam from said steam generator, means forreceiving the steam from said reducing means and for collecting solidmaterials thrown down by said reduction, and means for further reducingthe temperature of the fluid from said receiving and collecting means.

JOHN PHILLIPS BADENHAUSEN.

